1. Field of the Invention
The present invention relates to a piston bale press for forming rectangular bales of crop material.
2. Description of the Related Art
Such piston bale presses are for instance disclosed in EP 1 769 674, EP 0870 425, and U.S. Pat. No. 4,106,268, which are hereby incorporated by reference in their entireties.
EP 1 769 674 discloses an agricultural piston bale press, comprising:                a pressing piston arranged in a bale chamber to form bales or crop material        a main driving mechanism to drive the pressing piston in an oscillating movement in the bale chamber;        an intake device to take in crop material, and        a stuffing device to stuff crop material taken in by the intake device and to load the stuffed crop material to the bale chamber,wherein the stuffing device comprises a feed passage and a stuffing mechanism, the stuffing mechanism comprising an arm supporting tines which arm can be moved along a stuffing trajectory to stuff crop material in said feed passage and a load trajectory to load stuffed crop material from said feed passage in said bale chamber,wherein said arm is movable by a first driving device to at least move the tines in and out of the feed passage and wherein said arm is pivotably supported by a fulcrum, the fulcrum being displaceable to selectively move the arm along the stuffing trajectory or load trajectory.        
The arm of the stuffing device is connected to the main drive mechanism of the pressing piston via a mechanical linkage system, wherein one of the linkages comprises a telescopic element which can be brought in a non-blocked and a blocked position.
In the non-blocked position of the telescopic element the arm is moved along a stuffing trajectory, and in the blocked position of the telescopic element the arm is moved along a load trajectory. In the stuffing trajectory small cycles are made near the inlet of the feed passage to stuff crop material introduced by the intake device in the feed passage. When the crop material in the feed passage is sufficiently compressed, the telescopic element is blocked. As a consequence the arm will follow the load trajectory wherein the contents of the feed passage are transferred to the bale chamber of the pressing piston.
A drawback of the bale press of EP '674 is that the mechanical linkage system has a relative complex construction. Furthermore, the mechanical linkage system of EP '674 provides low flexibility with respect to the trajectory of movement of the arm.